Tumor-suppressing pathways in cystic pancreatic tumors

Introduction and Aims: Serous and mucinous cystic pancreatic tumors have different clinical behavior. We evaluated whether they also have genotypic differences by analyses of the tumor suppressor genes p16^INK4a, p53, and DPC4. Methodology: Seven serous cystadenomas (SCA) and seven malignant mucinous cyst-adenocarcinomas (MCC) were analyzed for alterations in the tumor suppressor genes p16^INK4a, p53, and DPC4 by single-strand conformational variant analysis, direct sequencing, and immunohistochemical analysis. Methylation-specific polymerase chain reaction analysis was performed to identify p16^INK4a promoter hypermethylation. Clinical data were compared with genetic data. Results: None of the seven patients with SCAs but five of the seven patients with MCCs died of the tumor after a median follow-up of 44.5 months (range, 4-169 months). All seven MCCs had alterations in at least one tumor suppressor gene compared with none of the seven SCAs. Of the seven MCCs, three had inactivating p16^INK4a promoter hypermethylation, five had p53 alterations, and three had DPC4 mutations. Conclusions: The tumor suppressor genes p16^INK4a, p53, and DPC4 appear to play an important role in the tumorigenesis of MCCs but not SCAs. These molecular data underscore the clinical and histologic differences of serous and mucinous cystic pancreatic tumors.